Electromagnet with resinous ferromagnetic cladding



June 13, 1967 J. A. BERNARD 3,325,760

ELECTROMAGNET WITH RESINOUS FERROMAGNETIC CLADDING Filed Oct. 1, 1965 INVENTOR James 0. Bernard il h' 1/18 AYTORNEY United States Patent 3,325,760 ELECTRDMAGNET WITH RESINOUS FERROMAGNETIC CLADDllNG James A. Bernard, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Filed Oct. 1, 1965, Ser. No. 491,928 4 Claims. (Cl. 335-281) ABSTRACT OF THE DISCLOSURE In the preferred form, an annular electromagnetic coil surrounds and is bonded to an iron ring with a resin having a high proportion of iron particles. The coil is encompassed by the same resinous material containing the iron particles which also extends on one side of the coil and the ring. A second resinous material containing a higher proportion of resin and a lower proportion of iron particles is bonded to the portion of the firs-t resinous material at the side of the coil and has projections formed thereon which engage recesses in a holding means forming a part of the adjacent driven device. In a second form, an iron ring encompasses and extends on one side of the annular coil. The resinous material extends on the inner and outer portions and one side of the coil and has projections extending into recesses on the inner side of the iron ring.

This invention relates to electric apparatus and more particularly to cladding arrangements for conducting magnetic flux around electromagnet coils.

It is customary to provide electromagnet coils with iron cladding to provide better conductance of the magnetic flux. It has been diflicult to uniformly fit the coils and the windings within the cladding to obtain the best conductance of the flux since the closer the wire cladding is to the coil, the greater is the conductance of the magnetic flux.

It is an object of the invention to provide a molded bonding means for improving and making more effective and eflicient the transmission of magnetic flux from an electrical magnet coil to an iron core or iron cladding.

It is another object of this invention to provide a magnetic flux conducting cladding arrangement which can be molded and integrally bonded to an electromagnet coil.

It is another object of this invention to provide a cladding arrangement in which a magnetic flux conducting molded material is provided between an electromagnet coil and the iron cladding.

These and other objects are attained in the forms shown in the drawings in which an annular electromagnet coil has bonded to it a molded cladding containing a maximum amount of iron powder and a minimum amount of bonding resin. This molded cladding may be used either alone or with inner or outer iron rings. In the latter form the iron resin molded cladding fills the space in between the iron ring and the coil and also extends around other portions of the coil excepting for an annular space providing a magnetic gap.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.

In the drawings:

FIGURE 1 is a sectional view of an electromagnetic clutch embodying one form of my invention;

FIGURE 2 is a transverse sectional view taken along the line 2-2 of FIGURE 1; and,

FIGURE 3 is a fragmentary sectional view similar to FIGURE 1 illustrating a modified form of the invention.

The construction of the clutch shown in FIGURES 1 and 2 is generally similar to that shown in Patent 3,082,- 933, issued Mar. 26, 1963, to which reference is made for additional details of construction. This clutch is, for example, mounted upon the compressor head 30, or other suitable device to be driven, which is provided with an integral tubular extension 42. In FIGURES 1 and 3 the compressor which is designated by the reference character 30 includes the compressor head. Within this extension 42 is a driven shaft 40 (FIGURE 2) connected by three leaf springs 66 to the ring shaped armature plate 70 of paramagnetic material such as low carbon steel. For attracting the armature plate 70 there is provided an annular coil 84 of many turns of insulated copper wire surrounding the tubular extension 42.

According to :my invention there is provided between and adhering to the coil 84 and the iron cladding ring 88 a molded flux carrying bonding material 89 which is composed of a maximum percentage of iron powder and a minimum percentage of resin to form a strong magnetic flux carrying molded bonding material which will transmit the flux from the winding 84 to the iron ring 88. For example, this molded material may be composed of 97% iron powder and 3% of a suitable bonding resin such as phenol formaldehyde resin. The iron ring 88 has a radial flange portion 92 provided on its left face with three or more integral projections 96 which interfit with corresponding recesses in the compressor head 30. The radial flange portion 92 on its right face has recesses 94 into which extend integral projections of the molded bonding material 89. The molded material 89 envelops the Winding 84 on all sides excepting the right side where there is a gap filled with a non-iron containing resin 86, which for example, may be composed 30% phenol formaldehyde and 70% asbestos fiber.

The drive pulley 121 has inner and outer rings 135 and 123 of paramagnetic material which cooperate with the coil 84 and its cladding to provide a magnetic flux carrying circuit which cooperates with the armature ring 70 to provide a very efficient magnetic circuit. The pulley 121 has in its malleable outer rim 123, a V-belt pulley groove containing a V-belt 125 providing a driving connection with a driving pulley not shown. The outer rim 123 is provided with a cylindrical flange 131 extending in telescoping arrangement with the cylindrical flange portion 98 of the iron ring 88 to provide an eflicient magnetic bridge thereto. The pulley rim 123 is also provided with a circular flange 133 extending in the opposite direction for providing a magnetic bridge with the armature ring 70.

The pulley 121 has an inner sleeve 135 of paramagnetic material such as malleable iron or steel concentric with and telescoping with the tubular extension 42, the coil 84 and the iron cladding ring 88 and flux carrying bonding material 89. It receives the outer race 137 of a double row ball bearing 139 which is mounted on the outer end of the tubular extension 42. The outer rim 123 and the sleeve 135 are 147 somewhat similar to brake lining material. It may contain phenol formaldehyde resin, asbestos fibers and aluminum chips.

With this arrangement the molded material 89 forms an eflicient bridge for magnetic flux between the coil 84, the iron ring 88 and the inner sleeve 135. The magnetic circuit is completed by the outer rim 123 of the pulley and the armature 70 which will be attracted upon energization of the coil 84 through its insulated terminals 110, 112 which extend through the molded cladding 89. By providing the molded flux carrying material 89 all around the coil 84 with the exception of the ring shaped gap filling resin 86, the magnetic flux is efliciently transbonded together by a molded material 3 mitted to the ring 88 and the sleeve 135 to provide a more powerful attractive force for the armature 70.

In the second form shown in FIGURE 3 a similarly efficient cladding arrangement is provided at a lower cost. This is accomplished by providing a thin cylindrical iron or low carbon steel ring 188 within the magnetic coil 84. The flux carrying molded material 189 in FIG- URE 3 takes the place of the iron ring 88 and the molded material 89 in between the ring 88 and the coil 84 in FIGURE 1. This molded material 189 includes a cylindrical flange portion 190 and an inwardly extending radial flange portion 192. This molded material 189 also extends between the coil 84 and the ring 188. There is also provided an intervening ring 186 of phenol formaldehyde resin and asbestos fiber molded in between the portions 190 and and the ring 188 to provide a non-magnetic gap.

The main portion of the molded material 189* is composed of maximum amount of iron powder and a minimum amount of resin sufiicient to give maximum magnetic flux carrying capacity with adequate strength, such as 97% iron powder and 3% phenol formaldehyde resin. However, the portion adjacent the compressor head 30 is a higher strength layer 193 which is composed of phenol formaldehyde resin and 90% iron powder. This high strength portion includes a number of projections 194 which extend into corresponding recesses 99 in the compressor head 30'. This higher strength layer provides increased structural strength for the projections 194 which interlock with the recesses 99 in the head to prevent the coil 84 and the iron or steel ring 188 and the flux carrying molding material 189 from rotating relative to the compressor head 30.

The molded cladding 189 and the ring 188 provides a very efficient means for conducting magnetic flux from the winding 84 on two sides to the flange 131 and the inner sleeve 135 of the pulley 121. The non-magnetic resin filled gap 186 forces the magnetic flux to flow through the magnetic circuit in the most efiicient manner. The winding 84 together with the ring 188, the molded cladding 189, and the resin 186- can be molded inexpensively to provide an efficient electromagnetic ring member.

While the embodiments of the present invention as herein disclosed, constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. An electromagnet including an electrical coil provided with electrical insulation, a holding means extending adjacent said electrical coil, a first flux carrying material containing resin and a high proportion of iron particles bonded to said coil wherein the improvement comprises a second flux carrying material having a greater proportion of resin and a lesser proportion of iron particles bonded to said first material and extending between said first material and said holding means and extending into surface contact with said holding means, said holding means and said second material being provided with an intergengaging arrangement.

2. An electromagnet as specified in claim 1 in which said second material and said holding means are provided with interengaging projections and recesses.

3. An electromagnet as provided in claim 1 in which the coil extends about an iron ring and the first material extends to and is bonded to said iron ring.

4. An electromagnet as specified in claim 1 in which a steel ring is located within said electrical coil and said first material encompasses the outer periphery of said coil and extends between one side of said coil and said second material.

References Cited UNITED STATES PATENTS 2,850,707 9/1958 Wroblewski et al. 336-83 3,162,285 12/1964 Sala 335281 X 3,201,729 8/1965 Blanchi et a1 335281 X 3,205,989 9/1965 Mantey 192-84 BERNARD A. GILHEANY, Primary Examiner.

G. HARRIS, Assistant Examiner. 

1. AN ELECTROMAGNETIC INCLUDING AN ELECTRICAL COIL PROVIDED WITH ELECTRICAL INSULATION, A HOLDING MEANS EXTENDING ADJACENT SAID ELECTRICAL COIL, A FIRST FLUX CARRYING MATERIAL CONTAINING RESIN AND A HIGH PROPORTION OF IRON PARTICLES BONDED TO SAID COIL WHEREIN THE IMPROVEMENT COMPRISES A SECOND FLUX CARRYING MATERIAL HAVING A GREATER PROPORTION OF RESIN AND A LESSER PROPORTION OF IRON PARTICLES BONDED TO SAID MATERIAL AND EXTENDING BETWEEN SAID FIRST MATERIAL AND SAID HOLDING MEANS AND EXTENDING 